Generate BootLoaderSpec config fragments

The BootLoaderSpec (BLS) defines a scheme where different bootloaders can
share a format for boot items and a configuration directory that accepts
these common configurations as drop-in files [0].

Generate BLS snippets at build time that can be copied on kernel install,
so bootloaders can parse to create menu entries using this information.

[0]: https://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/

Signed-off-by: Peter Jones <pjones@redhat.com>

generate_bls_conf.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+set -e
+
+. /etc/os-release
+
+kernelver=$1 && shift
+rootfs=$1 && shift
+variant=$1 && shift
+
+output="${rootfs}/lib/modules/${kernelver}/bls.conf"
+date=$(date -u +%Y%m%d%H%M%S)
+
+if [ "${variant:-5}" = "debug" ]; then
+    debugname=" with debugging"
+else
+    debugname=""
+fi
+
+cat >${output} <<EOF
+title ${NAME} (${kernelver}) ${VERSION}${debugname}
+linux ${bootprefix}/vmlinuz-${kernelver}
+initrd ${bootprefix}/initramfs-${kernelver}.img
+options \$kernelopts
+id ${ID}-${date}-${kernelver}
+grub_users \$grub_users
+grub_arg --unrestricted
+grub_class kernel${variant}
+EOF

kernel.spec

@@ -464,6 +464,7 @@ Source40: generate_all_configs.sh
 Source41: generate_debug_configs.sh
 
 Source42: process_configs.sh
+Source43: generate_bls_conf.sh
 
 # This file is intentionally left empty in the stock kernel. Its a nicety
 # added for those wanting to do custom rebuilds with altered config opts.
@@ -1104,6 +1105,7 @@ cp %{SOURCE1000} .
 cp %{SOURCE15} .
 cp %{SOURCE40} .
 cp %{SOURCE41} .
+cp %{SOURCE43} .
 
 %if !%{debugbuildsenabled}
 # The normal build is a really debug build and the user has explicitly requested
@@ -1518,6 +1520,9 @@ BuildKernel() {
 
     # prune junk from kernel-devel
     find $RPM_BUILD_ROOT/usr/src/kernels -name ".*.cmd" -exec rm -f {} \;
+
+    # build a BLS config for this kernel
+    ./generate_bls_conf.sh "$KernelVer" "$RPM_BUILD_ROOT" "%{?variant}"
 }
 
 ###
@@ -1829,6 +1834,7 @@ fi
 /lib/modules/%{KVERREL}%{?3:+%{3}}/build\
 /lib/modules/%{KVERREL}%{?3:+%{3}}/source\
 /lib/modules/%{KVERREL}%{?3:+%{3}}/updates\
+/lib/modules/%{KVERREL}%{?2:+%{2}}/bls.conf\
 %if %{1}\
 /lib/modules/%{KVERREL}%{?3:+%{3}}/vdso\
 /etc/ld.so.conf.d/kernel-%{KVERREL}%{?3:+%{3}}.conf\